Process for production of lubricating oil



June 25, 1935 U. B. BRAY ET AL PROCESS FOR PRODUCTION OF LUBRICATING'OIL Filed Aug. 4, 1951 BY ATTORNEY;

Patented June 25, 1935 UNl'lED .STATES PROCESS FOR PRODUCTION OFLUBBICATING OIL Ulric ana rams Verdes Estates, and Claude E. Swift,Huntington Park, Calif., assignors to Union: Oil Company of California,Los Angeles, Calif., a corporation of California Application August 4,1931, Serial No. 555,010

27 Claim.

This invention relates to a method and apparatus for treating petroleumto produce lubricating oil. 7

One of the distinctive characteristics of a lubricating oil is itsviscosity. For many purposes lubricants are preferred whiclr exhibitaminimum variation in viscosity with variations in temperature, i. e.,have low viscosity temperature susceptibility. It is generally knownthat the 10 viscosity of lubricating oil produced from Western crude,such as California naphthene base crudes, that is, crude containingasphalt varies more with change in temperature than do lubricating oilsproduced from parafiin base crudes. That is, if two such oils have thesame viscosity at 100 F., the Western oil will have a muchlowerviscosity at 210 F. than will the paraffin base oil. This change inviscosity with temperature is sometimes called the temperaturesusceptibility of an oil. It is one of the characteristics of Westernlubricating oils that they are distillates that is, are vaporized fromcrude oil and condensed. Lubricating oils produced from parafiin baseoils, containing substantially no asphalt, are generally produced byfirst distilling light oils overhead, including the kerosene and gas-oiland also taking overhead light lubricating oils called neutrals having aviscosity in the neighborhood of 100-200 seconds, Saybolt Universal at100 F., leaving an undistilled residue termed bright stock. The oils ofvarious viscosity are made by blending these neutrals and bright stockinany desired proportion to obtain the desired viscosity.

It has been observed by one of us that many oils containing asphalt andwax are mixtures of hydrocarbons analogous both to the hydrocarbonspresent in paraflin base oils and those present in asphalt base oils. Ithas further been observed by one of us that during the heating of an oilcontaining asphalt, the asphalt apparently induces certain chemical andperhaps certain physical reactions at relatively low temperatures whichtend to destroy the inherent low viscosity temperature susceptibility ofthe lubricating oil fractions. This apparent catalytic phenomena seemsto explain the observed changes although wedo not wish to be understoodas being bound by this theory. It has been observed that thesetemperatures at which the changes appear are below the (vacuum or steam)of the lubricating oil fractions which have Saybolt Universalviscosities above 400-500 seconds at 100 F. It is safe to say that nooil containing asphalt can be topped to the point where fractions above400-500 seconds,

vaporizer I05 is withdrawn through valve I02 Saybolt Universal viscosityat 100 F. are vaporv ized without a degeneration of thosecharacteristics of the paraffin hydrocarbons which'impart to the oil alow temperature viscosity susceptibilty. During the distillation of theheavy oils in the presence of asphalt some change in molecular structureor configuration takes place which is attended by a change of viscositytemperature characteristics. This behavior is thought to be due topyrolytic reactions which are catalyzed by 10 the presence of asphalt.The above discovery is made the subject matter of application Serial No.466,189. a

In order to preserve the inherent characteristics of the lubricating oilcomponents of crude 5 oil containing asphalt which are impaired bydistillationmethods 'as previously' described, we have, in accordancewith the process of the above application, caused the separation of theoil and wax from the asphalt by a method wherein the 20 lubricating oilconstituents present in the crude oil are separated from the asphaltpresent in such a manner that the oil retains those characteristicswhich it possessed in the original crude 011., As a means of'attainingthis end it has 25 been found advisable to cause the separation of theasphalt from the oil by means of solvents which are capable ofdissolving the oil and which do not dissolve the asphalt. Such solventsare light petroleum fractions, such as naphtha, cas- 30 ingheadgasol'meand petroleum fractions normally vaporous at ordinary temperature andpressure. Other solvents which may be used are alcohol, ether, mixturesof alcohol and ether, acetone, etc. We prefer to use as our solvent apetroleum fraction obtained by the rectification of natural gasoline.For most purposes a fraction composed of 6.72% ethane, 72.2% propane,19.91% isobutane and 1.17% normal butaneis satisfactory and is anexample of com- 40 mercially obtainable propane. .-This fraction ischaracterized by an average molecular weight and an average vaporpressure substantially the molecular weight and vapor pressure of purepropane. It will be understood, however, that these merely illustratethe type of fractions which may be used and that the composition mayvary. This fraction will hereinafter be referred to as propane forpurposes of simplicity. It is obvious that pure propane or commercialpropane, i. e., propane contaminated with methane, ethane, propylene,butane and the like, are equally applicable for use in our process.

In carrying out the extraction of the oil with this light liquidfraction the solution is maintained at a pressure sufilcient to maintainthe propane liquid at ordinary temperatures. The fraction describedabove is liquid at ordinary temperatures at a pressure of about poundsper square inch. The extraction of'the oil from the petroleum at suchpressures results in an asphalt substantially free of oil consistingchiefly of pure bitumen and a solution of oil and wax in the liquidpetroleum fractions. The oil dissolved in the liquid propane containssubstantially all of the lubricating oil components which are present inthe crude oil and in substantially the same form as they exist in theoriginal crude oil and also the major portion of the wax present in thecrude oil.

We have discovered that many lubricating oils obtained by extractionwith solvents, for instance, propane, from crude oil containing asphaltand wax are composed of oils which have a relatively high temperatureviscosity susceptibility and oils which have a relatively. lowtemperature viscosity susceptibility and that these oils may beseparated into oils which exhibit a low temperature viscositysusceptibility resembling oils produced from non-asphalt containingcrude and oils which exhibit a high temperature viscosity susceptibilitycorresponding to oils produced by distillation. For. convenience we willcall the oils which exhibit a low temperature viscosity susceptibilityparafflnoid and those which exhibit a high temperature viscositysusceptibility and resemble the Western lubricating oil distillatesnon-paraifinoid. The propane extract which consists of such a mixture ofparailinoid and non-parafilnoid oils may be separated into theserespective oils by the use of solvent agents which will selectivelydissolve out the non-parafflnoid components. We have found that certainsolvents have a selective solvent action for the non-parafllnoid oils.As solvent agents which will effect this separation we have found liquidsulphur dioxide, mixtures of acetone and benzol, aniline or methylformate useful. Acetone alone, in addition to being an asphaltprecipitant, also has in some measure the ability to split the oil inthe above manner. The use of liquid sulphur dioxide has been foundespecially valuable as a solvent to separate the propane extract intooils which exhibit low temperature viscosity susceptibility and intooils which exhibit high temperature viscosity susceptibility. As thepropane extract from the crude oil consists of a mixture of wax and oilnormally solid at ordinary temperatures, it cannot be separated into itsparafilnoid and non-paraflinoid components by the use of sulphurdioxide, without considerable difliculty, unless dissolved in a carryingmedium. We have found it advantageous to carry out the extraction of thewax oil mixture with sulphur dioxide in the presence of the liquidpropane usedin separating the asphalt. The wax oil mixture is dissolvedin liquid propane after which it is extracted with liquid sulphurdioxide to remove therefrom the non-paraflinoid components. The propanesolution of. parafilnoid oil is then chilled to precipitate the waxpresent after whichthe chilled mass is cold settled, centrifuged, orfiltered to separate the wax from the propane solution of oil. Byremoving the sulphur dioxide soluble bodies from the propane solution ofwaxy oil prior to the dewaxing operation we are able to obtain a finalproduct with a lower pour point, i. 'e., .wax content than could beobtained if the sulphur dioxide extraction operation were performedsubsequent to wax removal. The sulphur dioxide removes from oil certainbodies present which are good wax solvents and which have a tendency toprevent precipitation of the wax during the dewaxing operation.

The propane solution of oil recovered from the dewaxing operationsubstantially free of asphalt and wax may be further purified bytreatment with sulphuric acid. Such treatment removes from the paramnoil further impurities which were not removed from the oil by thetreatment with liquid sulphur dioxide.

Generally stated, it is the object of our invention to isolate fromcrude oil those oils having characteristics which impart, to it the lowtemperature viscosity susceptibility typical of paraffin base oil.

More particularly, it is an object of our invention to isolate fromasphalt containing oils those components which impart to the oil thereduced susceptibility to change in viscosity with temperature which ischaracteristic of oils obtained from non-asphalt containing oils; thatis, to separate the parafllnoid from the non-parafilnoid components ofthe asphalt containing crude oils.

It is a further object of our invention to separate asphalt from an oilcontaining asphalt, oil

and wax by means of a solvent, to separate the wax and parafiinoid oilfrom the non-parafllnoid oil by means of a second solvent used in thepresence of the first solvent, to separate the wax from the parafiinoidoil and thereafter to treat the paraflinoid oil dissolved in said firstsolvent with sulphuric acid.

It is a further object of our invention to separate oil and wax from anoil containing asphalt, oil and wax by the use of liquid propane; toseparate the wax and paraillnoid oil from the nonparafiinoid oil by theuse of liquid sulphur dioxide in the presence of liquid propane; toseparate the wax from the paraffinoid oil and thereafter to treat theparafllnoid oil with sulphuric acid.

Fig. 1 is one form of apparatus which we may employ to carry out ourprocess.

Referring more particularly to Fig. l, the crude which has beendistilled to remove light oils such as gasoline and kerosene and isitself a residual oil containing lubricating fractions, asphalt and waxin tank I is withdrawn through valve 2 and sent by means of pump 3through line 4 where it meets a stream of liquid propane coming fromtank i0 through valve ll, line l2, pump H5 and line l2. The mixture oftopped crude and liquid propane passes from line 4 to chiller 5 where aportion of the propane is allowed to vaporize through valve 6 and passesby means of line I to pump 32 where it is compressed and sent tocondenser 8 where it is liquefied and sent by means of line 9 to storagetank Ill. The vaporization of the propane in chiller 5 causes thetemperature of the mass therein to be lowered. The cool mass' '22 wherethe asphalt separates from the vapors and is withdrawn through valve 23and line" in the storage tank 25. The vapors in separator 22 arewithdrawn through line 26 into condenser 21 where the water vaporpresent is condensed.

' The condensed water-and propane vapor pass into separator 28 where thewater separates and is withdrawn through valve 29 and line 38. Propanevapor passes from separator 28 through line 8| to compressor lI3 -thenceto condenser 8 where it is liquefied and passes by means of line 9 tostorage tank I8.

The solution of oil in liquid propane in decanter I6 is withdrawnthrough line 33 and sent to chiller 84. A portion of the propane presentis allowed to vaporize by opening valve 35 and allowing the vapors topass through line 36 to compressor II8 where ibis compressed and sent tocondenser 8 and is liquefiedl thereafter being sent to storage tank I8.The vaporization of the propane in chiller 34 cools the mass which isthereafter withdrawn through valve.3'I, line 38 and sent by means ofpump 39 through line "to the lower zone of extraction column 4|. Liquidsulphur dioxide from tank 42 is withdrawn through valve 43 and sentbymeans of pump 44 through line 45 to the upper zone of extraction column4I. Due to the difference in specific gravity of the oil introducedthrough the lower zone of the extraction column and the liquid sulphurdioxide introduced into the upper zone of the extraction column, thesetwo liquids tend to separate. As the liquid sulphur dioxide descendsthrough the extraction column it dissolves certain components present inthe oil.

The solution of liquid sulphur dioxide and oil is removed from theextraction column 4I through the valve 46 and sent by means of line 41to vaporizer I where the sulphur dioxide is vaporized by aid of steamintroduced through closed coil WI and passes through line I86 tocompressor I8I where it is compressed and sent through line I88 tocondenser I89 where it is liquefied and sent to storage tank 42. Sulphurdioxide free oil in vaporizer I85 is withdrawn through valve I82 andsent through line I83 to tank I84.

The ascending column of oil in extraction column 4|, from which theliquid sulphur dioxide soluble components have been removed, passesthrough valve 48 to line 49 to auxiliary separator 58 where anyremaining liquid sulphur dioxide is settled out. A clear solution of oilis withdrawn from auxiliary separator 58 through line 52 where it may bemixed with a further quantity of liquid propane coming from storagetank' I8 through valve 53, pump I I4 and line 54. The solution of oiland propane carrying a small quantity of sulphur dioxide passes intochiller 55 where a portion of propane is allowed to vaporize by openingvalve M. The vaporized propane con-' taminated with sulphur dioxide,passes through line 62 to compressor I II where it is' compressed andsent through line 88 to condenser 89 where both the sulphur dioxide andthe propane are condensed and pass by means of line I I8 to separator 98where these two materials separate due to their great difference inspecific gravity. The liquid propane in separator 98 is withdrawnthrough valve 9I and sent by means of pump 93 through line 96 to storagetank I8. The liquid sulphur dioxide in separator 98 is withdrawn throughvalve 92 and sent by means of pump 94 through line to storage tank 42.The vaporization of the propane in chiller 55 cools the remainingsolution of oil present which passes out through valve 56 and line 51 topump 58 which forces it through filter press 59 where the precipitatedwax is removed through line 68.

The wax-free oil from filter press 59 passes through line 61 where itmeets a stream of sulphuric acid coming from tank 63 through valve 64,line 65 and pump 66. The mixture of acid and oil passes from line 61through agitator 68 where the mass is thoroughly agitated, after whichit passes through line 69 to separator I8 where the sludge is allowed tosettle out. The sludge in separator I8 is withdrawn through valve I5,line I6, to pump 11 which forces it through line I8 to heater I9 wherethe mass is heated sufficiently to vaporize the propane present. Theheated mass passes from heater I9 through line 88 to separator M wherethe sludge separates from the propane and is withdrawn'through valve 82and sent through line 83 to storage 84. The propane vapor is withdrawnfrom separator 8| through line 85 to compressor H 2 where it iscompressed and sent by means of line 88 to condenser 89 where it isliquefied and sent by means of line II8 to separator 98 where it isseparated from any liquid sulphur dioxide and sent by means of valve 9|,pump 93, line 96 to storage tank I8. The liquid sulphur dioxide inseparator 98 is withdrawn through valve 92 and sent by pump 94 tosulphur dioxide storage tank 42.

The acid treated oil in separator'18, dissolvedin propane carryingvarying amounts of sulphur dioxide, is withdrawn through line II andpassed through clay tower I2 where any remaining sludge is separatedout. 'The'fraction of oil leaving clay tower I2 passes by means of lineI3 to evaporator 14 where the propane and sulphur dioxide present arevaporized by aid of steam introduced through closed coil 9! and are sentby means of line 86 to compressor 81 where they are compressed and sentby means of line 88 to condenser 89 where they are liquefied and sent bymeans of line I I 8 to separator 98. Liquid propane in separator 98 isreturned to storage tank I8 through valve 9I, pump 93, and line 96. Thesulphur dioxide in separator 98 is returned to storage tank 42 throughvalve 92, pump 94 and line 95. The oil in evaporator I4 which is freefrom propane and sulphur dioxide is removed through valve 98 and sent bymeans of line 99 to refined oil tank I88. 1

As illustrative of the operation of our process for one type of oil andwithout intending to limit our invention,-water free residual oil intank I of Fig. 1 at a temperature of about 200 F. 15 mixed with liquidpropane and cooled by allowing a portion of the propane to vaporizeunder reduced pressure until the temperature of the topped oil andpropane is about F. after which it is thoroughly mixed in agitator I4.The thoroughly agitated mass is then passed into decanter I6 where thepropane solution of lubrieating all and wax is separated from theundissolved asphalt. This oil dissolved in liquid propane contains amixture of parafiinoid and non-paraiiinoid components. By subjectingthis mixture to the selective solvent action of liquid sulphur dioxidein the presence of liquid.- propane it is possible to resolve themixture into a portion of a non-paraflinoid nature soluble in liquidsulphur dioxide in the presence of liquid propane nature soluble inliquid propane. The wax present in the mixture being more soluble in theliquid propane than in the liquid sulphur dioxide remains in solution inthe former. This mixture of paraflinoid oil and wax dissolved in liquidpropane is then chilled to a point sufiicient to cause precipitation ofthe wax,- after which the chilled mass is filtered,- centrifuged or coldsettled to remove the wax. The wax-free solution of paraffinoid oildissolved in the liquid propane is then treated with sulphuric. acid toremove further undesirable bodies present, after which the sludge formedis settled out and the propane removed by distillation from the refinedoil.

The foregoing exemplary description is merely illustrative of apreferred mode of carrying out our invention and is not to be taken aslimiting, as many variations may be made within the scope of thefollowing claims by a person skilled in the.

art without departing from the spirit thereof.

We claim:

1. A process for producing lubricating oil from oil which comprisesdissolving said oil in a liquefled normally gaseous hydrocarbon,separating said oil dissolved in said liquefied normally gaseoushydrocarbon into a plurality of fractions with a selective solvent fornon-parafilnoidhydrocarbons and. subsequently separating the liquefiednormally gaseous hydrocarbon and solvent from said fractions.

2. A process for producing lubricating oil from oil which comprisesdissolving said oil in a'liquefied normally gaseous hydrocarbon,separating said oil dissolved in the liquefied normally gaseoushydrocarbon with sulphur dioxide into a plurality of fractions andsubsequently separating the liquefied normally gaseous hydrocarbon andsulphur dioxide from said fractions.

3. A process for producing lubricating 'oil from oil which comprisesdissolving said oil in a liquefied normally gaseous hydrocarboncontaining a major portion of hydrocarbons having less than four carbonatoms, separating said oil-dissolved in said solvent into a plurality offractions with a selective solvent for non-parailinoid' fractions andsubsequently separating the solvents from said fractions.

4. A process of selectively-extracting an oil into fractions whichcomprises commingling said oil with a liquefied normally gaseoushydrocarbon solvent, a major portion of which solvent consists ofpropane and a selective solvent for non-paraflinoid fractions of theoil, separating said oil into a plurality of fractions and separatingsaid fractions.

5. A process of selectively extracting an oil into fractions whichcomprises commingling said oil with a liquefied normally gaseoushydrocarbon containing a major portion of propane and ethane and asdective solvent for non-paraflinoid fractions of the oil, separatingsaid oil into a plurality of fractions and separating said fractions.

6. A process of selectively extracting an oil into fractions whichcomprises commingling said oil with a hydrocarbon solvent at least asvolatile as propane and a selective solvent for non-paraflinoidfractions of the oil, separating said oil into a plurality of fractionsand separating sai fractions.

' 7. A process of selectively extracting an oil intofractions whichcomprises commingling said oil with a hydrocarbon solvent having anaverage molecular weight less than butane and a selective'solvent fornon-parafiinoid fractions of the oil, separating said oil into aplurality of fractions and separating said fractions.

8. A process of selectively extracting an .oil into fractions whichcomprises commingling said oil with a hydrocarbon solvent having a vaporpressure greater than that of butane'and a selective solvent fornon-paraflinoid fractions of the oil, separating said 011 into aplurality of fractions and separating said fractions.

9. A process for theseparation of oil into with a liquefied normallygaseous hydrocarbon and a selective solvent for non-,paramnoid fractionsof the oil, cooling the mixture, separating a fraction dissolved in theselective solvent and removing the selective solvent and dissolvedfraction from the mixture. I

10. A process as claimed in claim 9 in which the cooling is obtained byvaporizing a portion of the liquefied normally gaseous hydrocarbon fromthe mixture. 4

11. A process for the separation of oil into fractions which comprisescommingling said all with a liquefied normally gaseous hydrocarbondiluent under superatmospheric pressure, releasing the pressure andvaporizing a portion of the diluent to chill the oil, extracting thecooled and diluted oil with a selective solvent for non-parafiinoid oilfractions, and separating the selective solvent and dissolved fractionsfrom the oil.

12. A process as claimed in claim 11 in which the selective solvent issulphur dioxide.

13. A'process for the separation of oil containing paraflinoid andnon-paraifinoid components into fractions which comprises comminglingsaid oil with a liquefied normally gaseous hydrocarbon and a selectivesolvent for-non-paraffinoid fractions of the oil, thereby forming arafilnate phase comprisingparafiinoid oil dissolved in the liquefiednormally gaseous hydrocarbon and an extract phase comprisingnon-parafllnoid oil dissolved in the selective solvent, separating saidphases and recovering the oil from said phases.

14. A process for the treatment of lubricating oil containingparafiinoid and non-paraflinoid oils which comprises commingling saidoil with a liquefied normally gaseous hydrocarbon and a selectivesolvent for non-parafilnoid oil, thereby forming a raflinate phasecontaining paraillnoid oil dissolved in the liquefied normally gaseoushydrocarbon and an extract phase containing non-parafiinoid oildissolved in the selective solvent, separating said phases andrecovering the 1 normally gaseous hydrocarbon and an extract.

phase comprising non-parafllnoid oil dissolved in the selective solventand separating said phases.

16. A process for the treatment of oil containing asphalt whichcomprises commingling said oil with an asphalt precipitating solvent todissolve the oil and precipitate the asphalt, separating the 4precipitated asphalt from the solvent solution of oil, extracting thesolvent solution of oil with a selective solvent for non-paraffinoid oilinto a plurality of fractions and separating said fractions.

17. A process as claimed in claim 16 in which the asphalt. precipitatingsolvent is a liquefied normally gaseous hydrocarbon.

18. A process as claimed in claim 16 in which the asphalt precipitatingsolvent is a liquefied normally gaseous hydrocarbon containing v a majorportion of propane.

19. A process as claimed in claim 16 in which the asphalt precipitatingsolvent is a liquefied normally gaseous hydrocarbon containing a majorportion of hydrocarbons of less than four carbon atoms. I

20. A process for the treatment of an oil containing asphalt whichcomprises 'commingling said 011 with an asphalt precipitating solvent toprecipitate the asphalt and to dissolve the oil, I

separating the asphalt from the solvent solution of oil, extracting thesolvent solution of oil with a selective solvent for non-parafflnoid oilto form a fraction dissolved in said asphalt precipitating solvent and afraction dissolved in said selective solvent, separating said fractionsand treating the fraction dissolved in the asphalt precipitating solventwith sulphuric acid.

21. A process as claimed in claim 20 in which the asphalt precipitatingsolvent is a liquefied normally gaseous hydrocarbon.

22. A process as claimed in claim 20 in which the asphalt precipitatingsolvent is a liquefied normally gaseous hydrocarbon and the selectivesolvent is liquid sulphur dioxide.

23. A process as claimed in claim 20 in which the acid treated oil istreated with clay.

24. A process for the treatment of oil containing asphalt whichcomprises commingling said oil with a liquefied normally gaseoushydrocarbon diluent to dissolve the oil and precipitate the asphalt,removing the asphalt from the oil dissolved in said diluent, extractingthe oil dissolved in said diluent with a selective solvent fornon-paraiilnoid oil to form a traction dissolved in said selectivesolvent and a fraction dissolved in said diluent, separating saidfractions, treating said fraction dissolved in said diluent withsulphuric acid and treating the acid treated oil with clay.

25. A process as claimed in claim 24 in which the liquefied normallygaseous hydrocarbon contains a major portion of propane.

26. A process as claimed in claim 16 in which the selective solvent issulphur dioxide.

27. A process as claimed in claim 16 in which the asphalt precipitatingsolvent is a liquefied normally gaseous hydrocarbon and the, selectivesolvent is sulphur dioxide.

- ULRIC B. BRAY.

CLAUDE E. SWIFT.

crnrmjcare 0F CORRECTION.

Patent No. 2,005,092. June 25. 1935.

ULRIC B. BRAY, ET AL.

It is hereby certified that error appears in the printed specificationof the above numbered patent requiring'correction as follows: Page 1,first column, line 50. forthe words "vaporizcr 105 is withdrawn throughvalve 102" read vaporizing temperatures in batch distillation; and page3, second'column, line 65 for the words "in the presence of liquidpropane" read and a portion of a paraffinoid; and that the said LettersPatent should be read with these corrections therein that the same mayconform to the record of the case in the Patent Office.

Signed and sealed this 19th day of .Novemher, A. D. 1935.

Leslie Frazer (Seal) Acting Commissioner of Patents.

